Field of the Invention
The present invention relates to examination portion information obtaining apparatuses, and particularly relates to an examination portion information obtaining apparatus utilizing a photoacoustic effect.
Description of the Related Art
A technique of detecting formation of a new blood vessel and oxygen metabolism of hemoglobin caused by growth of a tumor from an optical absorption property of the hemoglobin included in blood using light having a wavelength of approximately 600 to 1500 nm which has an excellent transmission property relative to a biological tissue so that results of the detection is used for diagnosis of the tumor has been used. Examples of the technique include a technique using a photoacoustic effect.
The photoacoustic effect is a phenomenon in which, when pulsed light of approximately nanosecond is irradiated on a substance, the substance absorbs optical energy due to an optical absorption property and is instantaneously expanded so that an elastic wave is generated. The elastic wave is detected by an ultrasonic probe so that a reception signal is obtained. When the reception signal is mathematically subjected to an analysis process, an absorption property in a living body may be represented by an image in accordance with sound pressure distribution of the elastic wave generated due to the photoacoustic effect. The hemoglobin is preferably used in a method for measuring the new blood vessel and the oxygen metabolism described above since the hemoglobin has higher absorptivity of near infrared light when compared with water, fat, and protein which constitute a body tissue. Clinical research to be applied to diagnosis of breast cancer and the like has been positively conducted using such a photoacoustic effect.
As a photoacoustic apparatus, International Publication Pamphlet No. WO2010/030817 discloses an apparatus including an acoustic wave detector which has a hemispherical shape and which includes a plurality of acoustic elements arranged thereon and a container having a cup shape to which a portion to be examined of a subject is to be inserted. This apparatus includes a photoacoustic detector having a hemispherical shape below the container and a light irradiation unit which irradiates light to a portion to be examined below the acoustic wave detector having the hemispherical shape. With this apparatus configuration, improvement of resolution of an information image obtained by receiving acoustic waves from the portion to be examined in a plurality of directions is realized.
When the apparatus according to International Publication Pamphlet No. WO2010/030817 is employed in an examination portion information obtaining apparatus for breasts, an examinee inserts a breast to the cup after positioning the breast in the cup-shaped container since the cup-shaped container is fixed to the apparatus.
However, when the breast is inserted in a state in which a position of the breast is shifted from the cup-shaped container, the examinee is requested to insert the breast in the cup-shaped container again by changing a posture so that a position of the cup-shaped container and a position of the breast coincide with each other. This operation is repeatedly performed until positioning between the cup-shaped container and the breast is within an allowable range. Accordingly, there arises a problem in that the examinee is forced to bear the burden. Furthermore, there arises a problem in that, when image information is obtained in a state in which the positioning between the cup-shaped container and the breast is out of the allowable range, reliability of the image information is degraded. Specifically, a measurement target portion in the breast may be located out of an imaging range.